A porous stamp assembly is typically fabricated by providing a porous impression die member with a transfer area (ink permeable area) having a seal pattern and a non-transfer area (ink impermeable area). In order to discriminatively form the transfer area (ink permeable area) and the non-transfer area (ink impermeable area) from each other, employed is one well known method of using a thermal head. In such a method, the thermal head with a plurality of heating elements and a platen permit the porous impression die member to pass therebetween and simultaneously compress the porous impression die member (to 95 to 30% of its original thickness), and the heating elements emit heat selectively as in a given print dot pattern including a character(s) and/or a drawing, so that the non-transfer area showing ink impermeability is defined in the impression die member while the remaining portion on which thermal effect is not exerted due to the inactivated heating elements is left as the transfer area showing ink permeability (see Patent Document 1).
Some other manufacturing methods of the porous stamp assembly include the well-known one that, in response to the demand of customers who want to prepare for a variety of stamping die faces, the process has stages of creating an impression die and of impregnating it with ink at the end of its sequence.
In this method, an ink reservoir is housed in a stamp frame, and the stages of creating an impression die and of impregnating it with ink cannot be carried out till the stamp is assembled to have an intermediate product with the impression die member securely adhered to the stamp frame, which after all necessitates the subsequent stamp product finishing stages, namely, the stage of using the thermal head to create the impression die and the final stage of pouring ink into the ink reservoir to impregnate the impression die member with ink (see Patent Document 2).
Another well-known stamp assembly manufacturing method directed to raising efficiency in yielding such porous stamp assembly products includes a process where after a porous impression die member provided with a dry impression die and a tank member wet or soaked with ink are incorporated in a casing, ink from the tank member is penetrated into the porous impression die member (see Patent Document 3).